The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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How Much Does Mounjaro Cost vs Wegovy in the UK?
If you're comparing Mounjaro and Wegovy in the UK, cost is often a key consideration — but price alone doesn't tell the full story. Both tirzepatide (Mounjaro) and semaglutide (Wegovy) are prescription-only GLP-1 medications available privately in the UK following clinical assessment. Prices vary between pharmacies and depend on which dose you're prescribed. Understanding both the costs and the clinical differences between these two medications can help you make an informed decision with your prescriber. Our GLP-1 weight loss calculator can help you explore potential outcomes at different doses.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Clinical Differences Between Mounjaro and Wegovy
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways rather than one. In the SURMOUNT-1 clinical trial, participants on the maximum 15 mg dose lost an average of 20.9% of their body weight over 72 weeks alongside a reduced-calorie diet and increased physical activity. Wegovy (semaglutide) is a GLP-1 receptor agonist only — it activates one pathway. In the STEP-1 trial, participants on the 2.4 mg maximum dose lost approximately 14.9% of their body weight over 68 weeks under the same conditions.
The dual mechanism of Mounjaro may offer slightly greater weight loss potential on average, though individual results vary significantly. Both medications slow gastric emptying and reduce appetite. Wegovy requires daily injections at lower doses or once-weekly at the maintenance dose, whilst Mounjaro is once-weekly from the start. A prescriber will assess which is more suitable based on your medical history, current medications, and personal preferences.
Clinically BackedWeight Loss
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Cost, Access, and Prescription Considerations
Both Mounjaro and Wegovy are available privately in the UK through GPhC-registered pharmacies following an online clinical assessment with a UK-licensed prescriber. Costs typically range from £129 to £320 per month depending on the dose prescribed — higher doses generally cost more with both medications. Neither medication is typically available on NHS prescription except through specialist tier 3/4 weight management services, which have significant waiting lists in most regions.
When comparing prices, remember that the "cheapest" option isn't always the best fit clinically. Eligibility, side effect tolerance, and suitability for your health profile matter more than price alone. Use our free BMI calculator to check your eligibility threshold, then discuss both options with a qualified prescriber who can recommend the medication most appropriate for your individual circumstances.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Is Mounjaro or Wegovy cheaper in the UK?
Prices vary by pharmacy and dose, but both typically cost £129–£320/month privately. Mounjaro's maximum dose (15 mg) and Wegovy's maximum dose (2.4 mg) may have different price points. NHS access is extremely limited — most people access these through private prescription.
Which one causes more weight loss — Mounjaro or Wegovy?
Clinical trials show Mounjaro achieved average weight loss of 20.9% at maximum dose, while Wegovy achieved approximately 14.9%. However, individual results vary greatly. A prescriber will assess which suits your health profile best, regardless of average outcomes.
Can I get Mounjaro or Wegovy free on the NHS?
Very rarely. Both medications are available through NHS specialist tier 3/4 weight management services, but access is limited and waiting lists can be very long (months to years in many regions). Private prescription is the main access route for most UK patients.
What's the key difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 agonist (activates two hormone pathways), whilst Wegovy is a GLP-1 agonist only (one pathway). This may give Mounjaro a slight edge for weight loss, but both are effective. Suitability depends on your individual health and prescriber assessment.
How do I know which medication is right for me?
Both require clinical assessment by a UK-licensed prescriber before prescription. Your prescriber will consider your medical history, current medications, side effect tolerance, and personal preferences. Use our GLP-1 weight loss calculator to explore potential outcomes, then discuss both options with your prescriber.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.